Low-Threshold Optical Bistability Based on Photonic Crystal Fabry–Perot Cavity with Three-Dimensional Dirac Semimetal

Round 1

Reviewer 1 Report

Low threshold optical bistability based on photonic crystal Fabry-Perot cavity with three-dimensional Dirac semimetal

Fengyu Li, Jiao Xu, Jianbo Li, Yuxiang Peng, and Mengdong He,

This manuscript by Li et al. theoretically analyzes the realization of Optical bistability in the THz regime using a 3D Dirac semimetal coupled to a Fabry Perot cavity utilizing a pair of photonic crystals. The tunability of the bistability threshold and hysteresis curve is demonstrated.  The authors also describe the optimum conditions to achieve a low bistability threshold in this scheme.

Some comments are given below:

1.       Line 44, please mention the advantages of using PhC instead of mirrors in the FP cavity in this scheme.

2.       As there are several DSM candidates listed in article line 60, What are the ranges for available E_F and σ for the DSMs listed here. What effect does this have on replacement of graphene as the candidate nonlinear medium? What relaxation times have been measured in these materials, to justify the variation of τ_S in Fig.4, and what would this depend on? σ₃ depends on relaxation time more strongly than on E_F. Answering these questions is essential to improve the general applicability of these results. Can a chart be provided to list these factors and a comparison of some candidate materials made to show which one is a promising candidate.

3.       Line 188, ψ is defined but is not shown in any of the previous equations. Please show where it is introduced.

4.       Line 192, it is stated that the Transmission decreases with increasing E_F, but it is not specified at what E_i. Are we talking of maximum transmission over entire range of E_i? At a specific E_i we see it actually increases with E_F.

5.       Where is eq. 18 (Line 201)

6.       Line 207, please show upper and lower threshold using arrows in the Figure 4.

7.       Line 224, where is the ϴ=6⁰ shown in the figure? It is 3⁰.

8.       To strengthen the paper, some more emphasis on the PhC aspect must be made. Why is N=4 chosen? What is the relationship of increasing N to the field confinement and transmission achievable? Can we increase T if we reduce to N=3? How was t₁ and t₂ chosen?

9.       The effect of incidence angle seems to be affecting field maximum at the midpoint of the cavity, leading to change in OB threshold. Can this be shown in a figure?

10.   Some other readability aspects are mentioned- Please label L_l and L_r in Fig. 1 or 2. Line 108 states eq. 4-3, but refers to eq 3 (i, ii). Please correct. Sometimes M_D is used, other equations use M_DSM. Please be consistent in usage. What is p_f in Eq 5?

Overall, this work is very similar to the work presented in Ref. 40 and does not bring sufficient novelty to justify publication. However, by increasing the amount of content specific to the PhC aspect, as well as the materials aspect of using DSMs other than graphene, we may be able to consider publication. But a lot of work must be done to increase the general applicability of these results. I cannot recommend publication of this work in the current state of the manuscript.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

In this paper, the authors investigate the tunable low threshold optical bi-stability at terahertz range based on photonic crystals Fabry-Perot (FP) cavity with three-dimensional Dirac semimetal theoretically. The article's title is suitable for the journal, and the article's topic is interesting for the readers. The report has several concerns that, if answered, would be suitable for publication.

1. What is the unit of E² in Figure 2(a)? It is better to write this unit as a caption on the figure.

2. What is the advantage of this research compared to previous researches? To compare the results obtained with similar works, it is better to add a table to the text and compare the results with previous works.

3. One-dimensional photonic crystals reflect light in only one dimension, but two-dimensional photonic crystals can reflect light in two dimensions. In other words, the light limitation is better in these crystals. Why did the author use a one-dimensional photonic crystal? To answer this question, it is better to refer to several articles using two-dimensional photonic crystals. Such as: https://doi.org/10.1007/s11082-023-04552-y, https://doi.org/10.1016/j.rio.2023.100375, https://doi.org/10.1364/AO.374428

 

 

 

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Can be accepted as sufficient revisions have been made.

Reviewer 2 Report

The revised version of the manuscript is suitable for publication.